End pieces of bed base

I have chosen to make this bed a double, and measured a bed I have here in stock, I need to cut these pieces 4 1/2 inches long, and then glue them to the inside of the bed posts, as you will see in the next pic.

PLEASE let each step dry before you continue, or you will find it will bend and wobble about and be very hard to work with. This will make for a more sturdy piece of furniture that is not crooked lol.